This section provides background information related to the present disclosure which is not necessarily prior art.
Conventional articles of footwear used in track and field events are typically constructed with a flexible sole structure having one or more cleats or spikes that aid an athlete in gripping the ground during use. For example, conventional articles of footwear used in track and field events have an outsole formed from foam or rubber and a series of metal spikes extending from the outsole. The foam or rubber material provides the article of footwear with a degree of flexibility while the spikes increase the ability of the article of footwear to grip the ground during use. Such increases in flexibility and grip aid the athlete during running, jumping, and lateral (i.e., side-to-side) movements.
While conventional articles of footwear used in track and field events adequately provide an athlete with flexibility and grip, such articles do not provide energy return to the athlete. Namely, when the sole structure of a conventional article bends, the general flexibility of the sole structure does not store a significant amount of energy. This is due in large part to the nature of the materials used in constructing the sole structure, as these materials are relatively flexible and, as such, require little energy to bend from a rest position to a flexed position. Accordingly, little energy is stored in making such movements and, therefore, little energy can be returned to the athlete when the sole structure is returned from the flexed position to the rest position.